Biofortification with chelating selenium in fragrant rice: Effects on photosynthetic rates, aroma, grain quality and yield formation

The main aim of the present study was to explore the effect of chelating selenium (Se) on aromatic rice performance. A field experiment was conducted in 2017 and 2018. At initial heading stage, five different Se solutions of 0, 10, 20, 30 and 40 mu mol L-1 were applied to rice leaves and named as CK, Se1, Se2, Se3 and Se4 treatments, respectively. The results showed 1.64-10.78 % higher seed-setting rate and 2.17-6.98 % higher 1000-grain weight in the chelating Se treatments than in the CK. Compared with the CK, the Se2 and Se3 treatments increased the grain yield and net photosynthetic rate by 8.24-14.65 % and 8.00-24.74 %, respectively. The Se2 and Se3 treatments also increased grain protein contents and reduced both the chalky rice rate and chalkiness. Moreover, the Se1, Se2 and Se3 treatments increased the grain content of 2-acetyl-1-pyrroline (2-AP) by 15.02-47.47 % compared with CK. The contents of proline, Delta 1-pyrroline-5-carboxylic acid (P5C) and 1-pyrroline (precursors in 2-AP biosynthesis) and the activities of proline dehydrogenase (ProDH), ornithine aminotransferase (OAT), and diamine oxidase (DAO) were also improved under the Se1, Se2 and Se3 treatments compared to CK. Furthermore, the chelating Se applications improved the total Se and Fe content in grains. The Se2 treatment was considered as the optimum concentration for chelating Se application in fragrant rice production.